Spark plug



D. A. ABBOTT.

SPARK PLUG. APPLICATION FILED SEPT.24. 1920.

Patented Sept. 19, 1922.

-W WW Snow M01 Tatented fiept. 3.9, 1922,

warren stares ear earner..-

DANIEL A. ABBOTT, 0F GREATER CAPITOL HEIGHTS, MARYLAND.

SPARK PLUG.

Application filed September 24, 1920. Serial No. 412,502.

T 0 all to 710m it may concern.

Be it known that 1, Damien A. rnno'r'r, a citizen of the United States, residing at Greater Capitol Heights, in the county of Prince Georges and State of Maryland, have invented certain new and useful Tmprovements in Spark Plugs; and I do hereby declare the following to be a full, clear, and exact description of the invention, such as will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in ignition apparatus for internal combustion engines, and more particularly to the arcing means in electrical ignition c rcuits.

The object in view is the production of a spark plug which is at once designed to largely prevent accumulation of carbon and capable of self-freeing from carbonand otherwise self-cleansing and assured against failure to produce an arc with each closing of the circuit.

A further object in view is the provision of means for insuring a hot spark of sufficient proportions for effective ignition of each successive fuel charge in which the arcing terminals of the spark merged.

With these and further objects in view as will in part hereinafter become apparent and in part be stated, the invention comprises certain novel constructions, combinations and arrangements of parts as subsequently specified and claimed.

In the accompanying drawing,

Figure l is a view partly in s de cl vation and partly in longitudinal vertical central section through a spark plug embodying the features of the present invention.

Figure 2 a transverse section taken on the plane indicated by line 22 of Figure 1 and looking downward.

Figure 3 is an enlarged detail side elevation of the piston detached.

Figures f and 5 are views similar, respectively, to Figures 1 and 2 of a slightly modilied embodiment of the invention.

Referring to the drawing by numerals, 1 indicates the usual metallic casing of a spark plug having the customary tubular porcelain or other insulator 2 secured within the casing by a retaining nut 3 of the usual commercial form. The customary packing de vices (not illustrated) are employed for pre venting leakage about or through the insuplug are subg lator 2. Extending throughout the insu lator 2, centrally thereof, is the rod 4 whose outer end portion is formed into the binding post 12 to which the umial lead (not shown) is connected. The inner end of rod 4: 1n the commercial types of spark plugs usually constitutes the central electrode while the lateral electrode projects from the inner portion of the shell or casing 1, but in the present improved construction the lateral electrode is omitted and the lower end portion of rod t does not serve directly as an electrode, the latter being supplement-- ed by a piston-like conductor 5. The con ductor 5 is a -tubular cylinder forming a piston head having an axially extending sleeve 6. The sleeve 6 is preferably reduced in diameter relative to the diameter of the piston head proper, so that when the head is moved outward under the influence of a charge being compressed, the sleeve will pass up 1nto the space 7 between the lower termlnal of insulator 2 and the rod 4:. The.annular shoulder 8 at the upper end of the head 5 produced by the juncture of the sleeve 6 therewith is of sufficientwidth to close the space 7 so that while the sleeve 6 in operation tends to remove any slight accumulations of carbon the shoulder 8 prevents access of burnt products to the exposed lower end of the insulator 2. The cylindrical surface of head 5 is substantially uniformly spaced from the inner cylindrical surface 9 of the lower end of shell 1 and the two surfaces serve as the electrodes between which the arcing occurs. In order to provide edges facilitating accumulation and disruptive discharge of current between the electrodes, the head 5 may be grooved longitudinally, as indicated at 10, 10, the grooves 10 extending on an incline with respect to the axis of the head. Each groove10,as best seen in Figure 2, is abruptly shouldered at one side and cut away at the other, the several shoulders of the grooves all facing in the same direction and being set substantially on the same pitch of inclination so that, in operation, as the passage of gases under compression into the shell 1 occurs only along the grooves 10 the impact of such gases'against the inclined shoulder of each wall tends to impart a whirling -motion to the head 5, while the action of the compressed charge against the inner end of the head tends to force the head outward, thatis toward the insulator 2. It is to be noted that the exterior surface of the head between the grooves is quite apformation of a the current sponding to the curvature of the inner surface 9 of shell 1, and the form of the head 5 is such as to insure effective shedding of oil or other foreign matter for providing clean portions of the cylinder head at all times, whereby arcing is assured and the non-arcing path of resistance is prevented.

In operation, as the compression stroke occurs in the cylinder with which the particular spark plug in question is in communication, the fresh charge being compressed acts to revolve the head 5 and press it upward toward a-seated position against the lower end of insulator 2. Of course, the head may not reach this position with each operation, especially when the engine is turning over under high speed. Thep1'otection of the insulator from carbondeposits and the removal of'such as may be deposited is, however, assured, and when the position of the piston for! firing has been reached, passing from conductingrod 4 to the piston electrode 5 bridges the gap betweensaid electrode and the point or points of the wall 9 or shell 1 oii'ering the path' of least resistance. Thus arcing may occur during movement of the piston 5 with a resultanhelongation of the arc which tends to increase its power to ignite the surrounding charge. Following the explosion and power stroke of the piston, the scavenging stroke thereof will tend to create a vacuum within the shell 1, sucking from about the lower end of insulator 2 such'gases as may have found their way'into the shell. This does not, however, proportionately tend to revolve the head 5 direction from its former movement, because the abrupt Walls of grooves 10 are'only at oneside. The discharging gases, however, do bring piston 5 down to itsinitial position at the inner end ofconductor 4L 1 The head 5 may be formed of the same material as shell 1, such as steel or brass, and, of course, the extreme lower end of the rod 45'i's'suiiiciently. burred or swaged at 11 to prevent escape of the piston 5 from the rod with the downward movement of the piston. Any appropriate detent may be em ployed in lieu of the swaged portion 11 for insuring retention of the head 5 against escape from the rod 4 while leaving the head free for reciprocal and rotary action thereon. In Figures 4 and "5 is shown a slightly modified embodiment of the invention, the

modification consisting essentially in omitting the grooves 10 from the piston head or electrode 5. Since the structure is otherwise ldentical, the same reference numerals have been applied and the same description applies to all parts save' the piston head con? insulator,

in the opposite,

gases, and being free to move ductor or electrode 5 which is shown formed as a complete cylinder having the sleeve .6

and slidingly mounted on the central conductor .rod 4. .In operation, the piston 5 functions 1n the same manner as piston 5,

except that it does not oscillate and its movement is substantially confined to reciprocation along the rod 4.

What is claimed is 1. In a sparkplug, the combination, with a shell, and an insulator extending into the shell, of a conductor extending through the the shell extending beyond the inner end of the insulator and a pistonlike electrode reciprocally and rotatably mounted on the conductor within the extended portion of the shell, the piston being formed with means for eil'ecting rotary action when influenced by moving gases, and being free to move axially and rotate under the influence of gases subjected to a com-- pression stroke. f

2. In aspark plug, the'combination, with. a shell, and an insulator extending into the shell, of a conductor extending through the insulator, the shell extending beyond the inner end of the insulator, and a pistonlike electrode reciprocally and rotatably mounted on the conductor within the extended portion of the shell, the piston being formed with means for effecting rotary action when influenced by moving gases, and being free to move axially the influence of gases subjected to a compression stroke, the insulator being formed with an annular space at its inner end portion about the conductor and the pistonlike electrode being formed with a sleeve extending in the direction toward the in- 'sulator and proportioned to move into and 3. In a spark plug, the combination with a shell and. an insulator extending into the shell, of a conductor extending through the insulator, and a piston-like electrode reciprocally mounted on the conductor, the said electrode being substantially cylindrical and being formed with peripheral grooves, said grooves being disposed at an incline 'to the axis of the piston for causing the piston to be rotated under the impact of, passing axially and rotate under the influence of gases subjected to acompression stroke. In testimony whereof I aflix my signature in presence of two witnesses." I DANIEL A. ABBOTT. Witnesses:

CHnIs'rIn H. FESLER, EDGAR M. Krro'HIN.

and rotate under 

